How does their proposal compare to Microsoft’s Web Tracking Protection Member Submission? A few observations. Most importantly, draft-mayer focuses on the opt-out header; it doesn’t cover either the tracking list idea or the DOM property defined in the submission. Further, the draft distinguishes between three (not two) states: DNT: 1 (“I don’t want to be tracked”), DNT: 0 (“it’s ok to track me”), and no header — the latter case is called out explicitly as “no preference.” Another interesting addition is the use of DNT as an HTTP response header: The protocol proposed here is that Web sites that support “do not track” play the header back when they send a page, and that clients (and others) can use that to keep statistics about who’s respecting an opt-out.

Also worth comparing: The two statements on what “do not track” actually means. At first glance, they’re quite different in scope and in level of detail; Mozilla’s version has a long initial set of exceptions. Drilling down on what direction the definition of “do not track” should take will be an important agenda item for April.

Meanwhile, on the political stage: As the BBC reports, EU Member States aren’t prepared to actually enforce a European Directive about cookies and user tracking. Instead, we can expect the debate about behavioral advertising, opt-outs, and tracking protection lists to take center stage in Europe as well.

All of this suggests some interesting discussions in the Web Tracking space at the April workshop: Which of the tracking protection mechanisms are a good idea? What are the merits of the various design options? How do they interact with different cultural and legal expectations around the globe? Which ones should we take up for standards work at the W3C? What’s the right coordination story for this work?

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